Self-leveling hydraulic lift system



June 6, 1950 Twls'r SELFLEVELING HYDRAULIC LIFT SYSTEM 3 Sheets-Sheet 1 Filed De@ 16, 1946 INV/NTM e, m wm mm. n..

Jun'e 6, 1950 L., E; TWIST SELFA-LEVELING HYDRAULIC LIFT .SYSTEM 3 Sheets-Sheet 2 Filed Dec. 16, 1946 f ll- I.. l-...NIV

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m IVI June 6, 1950 L. E. 'rwlsT .SELF-LEVELING HYDRAULIC LIFT SYSTEM v.Fi-lied Dec. 1s, @E946 "3 SheetS-Sheet 3 #Harney amaaiv :une s, 195o UNITED STATES PATENT OFFICE' SELF-LEVELING HYDRAULIC LIFT SYSTEM.

I Lee E. Twist, Los ngelemAClif. lApplication December 16, 1946, Serial No. 716,587

Claims. (Cl. 60-97) i This invention relates to hydraulic Vleveling equipment, which may be utilized for such 'ourposes asfor automatically leveling the bed of harvesting combines and arranged between the bed and the axles thereof; leveling large air planes prior to nigging, and arranged between the. under surface thereof' and the ground 0r floor; or leveling trailers used as living quarters. The invention will be particularly described hereinafter as applied to the last mentioned specific application by way of example only.

Other objects include: the provision o1 means for automatically leveling the supported structure under the influence of hydraulic pressure; means for automatically locking the apparatus in self-leveled position when such position is attained; a plurality of lifting units disposed at spaced pointsv under and for supporting a structure; means for inter-connecting said Supporting umts with a source of fluid; `and means for controlling the ow of fluid from certain points to others so as to balance the pressure at all supporting points.

Still other objects will appear as the description `of my improvementsprogresses.

A satisfactory system and apparatus is shown in the annexed drawings, subject to modication within the scope of the appended claims.

In the drawings:

Fig. 1 is a perspective view of a vehicular trailer with my lifting apparatus applied thereto and illustrative of one use of the apparatus;

Fig'. 2 dsa perspective view of one of the lifting units;

Fig. 3 is an enlarged vertical section of the same;

Fig. 4 is a transverse section of a unit on line 4-4 of Fig. 2;

Fig. 5 is an external view of a unitas viewed in the direction of the arrow 5 in Fig. 4;

Fig. 6 is a sectional view on line 6-6 of Fig. 5;

Fig. '7 is a sectional elevation of a fluid storage tank and associated parts;

Fig. 8 is a section of the storage tank on line I-8 of Fig. 7;

Figs. 9, 10 and 11 are sections oi the .tank on lines 9 9, Iii-I0 and respectively, of Fig. 8;

Figs. 12 and. 13,I are, respectively, sectional views on lines |2|2 and |3|3 of Fig. l0;

Fig. 14 is a schematic diagram showing a control unit in section and a uid tank in phantom, a plurality of lifting units and connections therebetween; and

Fig. 15 is a sectional elevation of a brake unit for holding an associated ram in adjusted position.

Mysystem includes a storage tank T for holding a quantity of fluidl and connected on the suction side with a pump P and thence to a plurality of control valves V, Vi, and Vn and then to a plurality of hydraulic rams R, Ri and R2. There are two lines from each valve to each ram, one feeding fluid under pressure to the ram and the other returning iiuid from the opposite side of each vram to the tank. As shown in Fig. l, the ramyunits are applied to the bed of a trailer A, for instance, with a single unit R, at the front and .in the center-and two ,units Ri and R3 at the rear backwardly of the rear wheels, thus providing three point suspension for the trailer.

Each unit, as at R in Figs. 1 to 4 inclusive, has a vertically disposed movable cylinder ||l arranged with a bottom and a ball |2 adapted to seat in a socket |3 of a foot Il and t0 be selfadjusting to the surface of the ground upon which the foot rests, and a fixed piston 2|.

The upper ends of the pistons are fixed to brackets |5 which have one or more webs adapted to be attached to the trailer frame l1, as shownv in Fiig. 2. Each cylinder has a packed head i9 through which a hollow piston stem 20 is extensible from cylinder ||l as said cylinder is relatively moved. As shown in Fig. 3, pistons 2| have upper and lower portions 22 and 23 between which peripheral packing 24 is compressed. Stem 20 fits into a recess in upper part 22'against an inner ilange 25 and a member 26 is screwed into the end of said stem for drawing parts 22 and 23 together and thus holding the pistons assembled for use. Piston 2| divides the cylinder into two chambers 28 and 30.

Members 26 are bored to receive inlet tubes 21 through which a iiuid is admitted to chamber 28 of a cylinder below piston 2|, while stem 2|) has ports 29 at points above the piston for directing iiuid from upper chamber 30 into the passage 3| of the stem and thence outwardlyA as hereinafter described.

Each ram unit includes .a xture 32 attached to the upper end of stem 20 and rigidly braced to bracket I5 as by means of bars 33. Fixture 32 has a fluid inlet 34 connected through tube 2l with chamber 28, and an outlet 35 in communication with chamber 30 through passage 3| vcylinder will descend'relative to piston 2| and through the fixed connection of the piston with frame (bracket I5. bars 33 and ilxturen) the 3 frame will be elevated, and as fluid is exhausted from chamber 28 but pumped into chamber 2 9, the cylinder will be raised.

I refer now to Fig. 14, which shows a hydraulic lift system in which the rams R, R1 and R2 are connected with other essential elements. First,

' the storage tank T is arranged for holding a necessary quantity of operating fluid for dispersal to the several rams and for receiving the used fluid at the completion of or during the operation of the system. The pump P is connected by means of a pipe 35 with the outlet from tank T and serves to withdraw the fluid from the tank and deliver it to points throughout the system as and when required, but preferably through a pipe 36 to an inlet 31, leading to a check valve 38 in a chamber 38a which serves to hold pressure in the system under certain operating conditions to be hereinafter explained. Chamber 38a has a bleeding passage 38e open to the tank T.

Each ram R, R1 and R2 has a control valve V, V1 or V1, respectively, which is carried by a suitable block.39 preferably mounted in tank T above the level of fluid. Said block also supports check valve 38, restrictor valves 40 and 4| and an operating handle 42. Said block is adapted to be xedly supported in the upper portion of tank T (Fig. '1). A pendulum 43 is pivotally supported by shaft 44 turning in arms 45, 45 of a yoke 41 which straddles block 39 so that the pendulum may freely swing in the fluid of tank T to an extent limited only by' a pair of spaced ballles 46, 46 xed to the bottom of the tank as shown in Fig. '1. Yoke arms 45 are cross connected above block 39 by a rod 48. Pendulum 43 may also swing on shaft 49 (Fig. 8) mounted in shaft 44 perpendicular thereto, forming a gimbal mounting, and is gravity actuated for regulating valves V, V1 and V2 in accordance with the inclination of the supported structure A.

As shown in Fig. 14, the control valves V, V1 and V2 are slidably mounted in bores 50, 5| and 52, respectively, formed in block 39 and are open at opposite ends to-tank T, and have upper enlarged portions 50a, 5|a and 52a and similar lower portions 50b, 5|b and 52h which fit their respective bores 50, and 52. Inter-communication between valve bores 50, 5| and 52 is effected by passages 53 having suitable branches and connecting with valve chambers 54 and 54a of valves 40 and 4| at times so that uid from pump P may flow by check valve 38 and its chamber 38a and a passage 38h by valve 40 into passage 53 under pressure from the pump against the tension of a spring 40a which tends to hold valve 40 closed. Likewise, pressure in passage 53 at times will open valve 4| against the tension of its spring 4|a so that uid may ow into a chamber 55 through a port 55a (Fig. 14). Chamber 55 has a bleeding passage 55b to tank T. A piston 56 is slidable in chamber 55 under the control of pressure from pump P and operates member 42 in the form of a yoke 58 with external arms 59, 59 pivoted to opposite sides of block 39 at coaxial points 60, 60 and connected by a rod 6| to which a knob 62 is attached. (See Figs. '1 to 10, inclusive.) Rod 6| engages the surfaces of a V- shaped groove 63 in the outer end of piston 56 so that as the operating member 42 is swung upwardly or downwardly from a normally central position, the piston 56 will be forced inwardly in chamber 54 for purposes hereinafter explained. A spring 63a is arranged between the side of the tank and rod 6|. Yoke arms 59 extend across connected by tension springs 68 with the-tips of valves V, V1 and V2, the springs acting to hold short lengths of rod 69, having a ball and socket connection with the ends of the valve stems and arms 43a, 43h and 43o, under tension to provide a suitable joint between the parts, so that 4as the pendulum 43 swings in any direction one -or more of the control valves will be moved to a position for leveling the supported structure.

Referring to Fig. 14, itwill be observed that the inlets 34 of ram heads 32 are connected by pipes 10, 1| and 12 with'ports 10a, 1|a and 12a, respectively, opening into valve chambers 50, 5I, and 52 which are regulated by portions 50a, 5|a and 52a of valves V1, V, and V2. Also, outlets 35 of ram heads 32 are likewise connected by pipes 13, 14 and 15, respectively, with ports 16, 11 and 18 leading to valve chambers 50, 5| and 52 at points closeable by portions 50h, 5|b and 52h of valves V1, V and V2.

In Fig. 14 I have indicated an accumulator B, f

which has a housing and an internal diaphragm 86 serving to divide housing 85 into two chambers 81 and 88, for,` respectively, receiving fluid and air under pressure. Chamber 81 receives surplus fluid and surplus pressure during the raising operation of the rams through a pipe 89 and a passage 89a connected with valve chamber 38a while chamber 88 is charged with air through an inlet valve 90. The accumulator supplies pressure fluid during the leveling operation.

It will be understood that, due to the unevenness of the terrain on which a vehicle may be set, it is necessary to individually hold the several rams in relative positions for maintaining horizontality of the supported vehicle and for such purpose I provide a brake unit on each ram. Such a unit is illustrated in Figs. 5 and 15, and includes a xture carried by bracket |5 (Fig. 4), cylinder 96 secured to fixture 95, a piston 91 in said cylinder, and a shoe 98 (see Fig. 3), secured at top and bottom by the bracket but having a cut out portion intermediate its ends and adapted to be clamped against the cylinder |0 of an associated ram.

As shown, particularly in Figs. 4, 5 and 15, two pairs of cams 99 are mounted-one pair at the top and one pair at the bottom-of fixture 95, and are inter-connected as by means of one or more rods |00. Said cams are formed by bending up a sheet metal blank to provide a cam flange 99 at each side of a web of metal 99a. The cams are pivoted on shafts |0| and |02, respectively, supported in the walls of the xture 95 with their heels |03 abutting the outer'surface of shoe 98 and their toes |04 connected to rods |00 so that they will operate together. One or more tension springs |05 are connected at |06 to one pair of cams 99 while the opposite ends of said springs are aixed to a stationary part of housing 95, thereby tending to commonly actuate both of the cams for urging shoe 98 into engagement with cylinder I0. Preferably, a friction lining 98a of suitable material is carried in the known manner by the shoes 98.

` 6 Cylinder n stationarily held on housing l and piston l1 is movable by iluid pressure so as to operate thecams lat times. To such end pis-v ton l1 has a piston rod Il1 which engages at least one cam 5! and, as shown in Fig. 15, urges all of the cams into disengaged positions of nonfrictional engagement, and permits movement of the ram relative to its shoe 5l, against the tension of springs |05.

A fluid inlet and outlet 4|05 is provided below piston l1 in cylinder 56 for admitting iluid'under pressure into the cylinders to raise the piston and exhausting the same from the cylinder 96 when the piston 91 is returned by the springs |05 as the fluid pressure in the system is lowered. A compression spring |09 is carried to the bottom of cylinder il for holding piston rod |01 in contact with the cam and tends to hom the piston 1n proper position in the cylinder when the pressure below the piston is insuillcient to hold cams 99 in inoperative position. Inlets |08 are commonly connected with a pipe leading from units R, R1 and R: to chamber 38D of block 39. Thus, as operating handle 42 is moved downwardly and 4held in that position pump P is activated by switch S (Fig. 7) arms 41 will be raised, raising arms 45 and raising pendulum 43 thus causing arms 43a, 43h, 43c to open valves 50a, 5|a, 52a to pressure fluid and opening the valves 5b, 5|b, 52b`to exhaust iluid from above the rams to the tank. Fluid uder pressure from the pump will tlow past check valve 38 into'chambers 38a and b charging the accumulator and also will ilow through pipe |||l to each brake unit and will raise pistons 51 and retract cams 99 for releasing brake shoes $8 from ram cylinders Ill. When sumcient pressure has been built up the pressure uid will raise valve 40 and ilow through passage 53 and its branches into valve bores 50, 5| and 52 supplying pressure through pipes 10, 1| and 12 to chambers 2l of the ram units through their inlet tubes 21. The cylinders ||l are thus forced downwardly into contact with the ground and the supported structure A is raised. Fluid between the top of the cylinders and the pistons will be returned to the tank through pipes 13, 14, 15. If the structure A is on level ground, all of the valves and rams will operate alike, but it the ground is uneven or inclined in any direction, the valves V, V1 and V2 and associated units R, R1 and Rz will vary as to their relative extent of operation until the structure A assumes horizontality. The leveling operation is always under the control of pendulum 4-3 which regulates the movement ot valves V, V1 and V1 by reason of the connections between the tips 69 of said valves and the yokes of the pendulum. Thus, as the pendulum swings in any direction, one or more of the control valves will move upwardly or downwardly according to a given inclination of structure A and thereby open or close, or regulate the eiectlve open area of ports 50a., 5|a and `52a for directing hydraulic pressure to the cylinders lli.

When a predetermined pressure on rams R, R1 and Rz (Fig. 14) has been attained, which is adinstable by spring 54a on ball 4| for the particular load, fluid will now through passage 55a into chamber 55 forcing piston 56 against cross arm 6|. The V-slot in end of piston 56 will move operating handle to central position, raising saddle 41 (Fig. '1) pendulum 43 and valves V, V1, Vz and inactivate the pump by releasing switch S1. This is the leveling period, at which time the accumulator 88 (Fig. 14e) will come into action. All valves V, V1 and V1 will have closed their ports only if pendulum 42 (Fig. '1) is in plumb with the trailer trame, out of plumb position of the pendulum will control the valves accordingly, raising or lowering individual rams R, R1, R2, and hold the position attained until the accumulator has exhausted itself through bleeder passage 38e (Fig. 14), enabling springs |05 to pull the pistons downwardly exhausting iluid'through pipe ||l and applying cams 99 against shoes ll locking all rams in this ,fixed position.

When operating member 42 is moved upwardly, pump P is switched on by switch S and operation is reversed since the return ports 50h, 5|b and 52h are opened by` the lowering of yoke arms 45. Fluid will again be pumped into cylinders 96 to release the brake, and into spaces Il! returning the rams to telescoped position.` The uid will thereafter also be exhausted as before from under pistons 91 allowing the cams 99 to clamp the rams in withdrawn position. Fluid in chambers 28 of cylinders I0 will be exhausted through outlets 10', 1|, 12, passages 50a, 5|a, 52a

over the upper valves V, V1, V1 and into the tank.

While I have described and illustrated a preferred embodiment of my invention, it is to be understood vthat various modiilcations and rearrangements of parts may be made by those skilled in the art without departing from the scope of the invention as intended to be deilned by the appended claims.

1. A leveling device for structures including: a pendulum suspended from said structure andfree to swing in any direction; a plurality of hydraulic rams mounted below said structure and adapted to be projected against a supporting surface; a pump; conduits connecting the output from said pump to said hydraulic rams; valves controlling said conduits; operative connections between said valves and said pendulum whereby movement of the pendulum operates the valves if the structure is not level, to supply liquid under pressure to particular rams to bring the structure into level position; means to operate said pump to supply tluid under pressure to said` valves; locking means fltted to said rams; resilient means normally holding said locking means in position to prevent movement oi' said hydraulic rams, hydraulically operated means eiective to release said locking means; conduits connecting said hydraulic means to the pump output so that the locking means are released when pressure iluid is supplied by the pump to the system; operative means for manually puttingthe pump into operation and i'or automatically putting it out of operation ,on a predetermined pressure of the hydraulic fluid being attained; spring loaded valve means eilective to maintain the hydraulic pressure on the rams when the pump is put out of operation; and an escape conduit between the lpump and said spring loaded valve connected to said hydraulically operated releasing means whereby hydraulic pressure is released from said means and the locking means are brought into action to hold the structure in level position.

2. A device as set forth in claim 1 and in which said source of uid under pressure comprises a prime mover and pump driven thereby serving to supply fluid under pressure to said conduits, said means for setting the device into operation comprising a handle manually moved from neutral position to start said prime mover into operation and automatically returned to neutral position to stop said prime mover when the pressure i in all parts of the system has become stabilized.

3. A vdevice as set forth in claim 1 and in which the hydraulic rams are double acting; movement of the operating means in the direction opposite to that putting the device into leveling operation acting to withdraw the hydraulic rams into telescoped position.

4. A device as set forth in claim 1 and in which said valves are positioned in a valve block; and a tank for hydraulic iuid secured to the structure in which said valve block and pendulum are arranged.

5. An automatic leveling system for structures including: a plurality of telescopic units applicable to and disposed at different points between the structure and a supporting surface therefor; a source of fluid under pressure, a freely swinging pendulum, and a valve block, -both said pendulum and valve block being enclosed in a uid containing housing; valve control means operated by said pendulum and also located in said housing; including inlet and outlet valves for each of the telescopic units; conduits connecting 8 operation. and to automatically cause termination of the operation of the device on the structure attaining a predetermined position, the operation of said latter means being independent of the level of the uld in said housing.

LEE E. TWIST.

REFERENCES CITED The following references are of record in the file of this patent: I

UNITED STATES PATENTS Number Name Date 955,852 Coyle Apr. 26, 1910 1,085,964 Briggs Feb. 3. 1914 1,344,037 Heymann June 22, 1920 1,906,965 Hobson May 2, 1933 1,948,951 Walker Feb. 27, 1934 2,132,184 Poche Oct. 4, 1938 2,229,530 South Jan. 21, 1941 2,278,081 Kramer Mar. 31, 1942 2,323,731 Shetzline July 6, 1943 2,342,812 Martinson Feb. 29, 1944 2,349,244 Brown May 23, 1944 2,380,973 Kopp Aug. 7, 1945 2,434,949 Mueller Jan. 27, 1948 2,440,948

Hawkins et al. May 4, 1948 

